This invention relates generally to drainage systems and particularly to drain traps in such systems.
The state-of-the-art known by the applicant refers to general drain traps in buildings. These are installed before the connection to the sewer network, to prevent effluences and foul odors from the sewer from spreading through the building drainage network to the interior of buildings and through the drains of terraces and patios. The problem posed in this case is that it is impossible to anticipate when blockage will occur, which is generally due to the discharge of solid materials or to accumulation of deposits that are not carried away by the water, or to solidification of detergent scum that accumulates in the general trap.
Referring to FIGS. 1–4, the prior art drainage system comprises an inlet pipe 2 and an outlet pipe 4. Disposed between the inlet pipe 2 and the outlet pipe 4 is a general trap section 6. Manholes 8, 10 are disposed within the inlet pipe 2 and outlet pipe 4 respectively. In use, the general trap section 6 fills with water to the level of line 12 and prevents the smell of sewage from passing from the outlet pipe 4 to the input pipe 2. Referring to FIG. 4, when the trap 6 becomes filled with a blockage A or a blockage B, the sewer becomes clogged and no water flows through the inlet pipe 2 to the outlet pipe 4. When the water level falls below that shown in FIG. 4, the trap fails to prevent the smell of sewage passing from the outlet pipe 4 to the inlet pipe 2.